Pad of stacked detachable sheets,and method and elements for manufacturing the same

ABSTRACT

A new pad having a rigid stub and stacked detachable sheets is made by interposing between and two adjacent sheets at least one film of heat- activable glue, heating said stub portion to the activating temperature of said glue, applying pressure on said stub portion maintained at said temperature, then cooling the assembly at room temperature. When the sheets are to be printed, the film of glue can preferably be replaced by a printing coating on a face of the stub of the said sheets, with a thermogluing ink. This new pad can advantageously be used as a calendar.

J..LAVIGNE SH Dec. 11, 1973 3,778,324 METHOD SAME 2 Sheets-Sheet 1 PAD OF AND Filed March 17, 1971 DETACHABLE EETS AND TS FOR MANUFACTURING THE C EM FIG.1

I J. LAVIGNE PAD OF STACKED DET AND ELEMENTS F0 Dec. 11, 1973' ACHABLE SHEETS, AND METHOD R MANUFACTURING 'THE SAME 2 Sheets-Sheet 2 Filed March 17, 1971 m. w 1.5% U I A. M I fi m h 5 FIG. 7

United States Patent US. Cl. 156257 3 Claims ABSTRACT OF THE DISCLOSURE A new pad having a rigid stub and stacked detachable sheets is made by interposing between any two adjacent sheets at least one film of heat-activable glue, heating said stub portion to the activating temperature of said glue, applying pressure on said stub portion maintained at said temperature, then cooling the assembly at room temperature.

When the sheets are to be printed, the film of glue can preferably be replaced by a printing coating on a face of the stub of the said sheets, with a thermogluing ink.

This new pad can advantageously be used as a calendar.

This is a continuation-in-part of my copending application Ser. No. 888,481, filed Dec. 29, 1969, now abancloned.

The invention relates to pads of detachable sheets and more particularly to pads having a rigid stub and stack detachable sheets such as those conventionally used as calendars.

The conventional pads of the calendar type are generally constituted by a support sheet of cardboard onto which is glue or otherwise fastened a stack of at least partially detachable sheets. Some of these pads are assembled by gluing together the edges of all the sheets constituting the pad, while one paper sheet is generally glued onto the cardboard supported so as to constitute a linking element and form at the same time a cover sheet. Especially the known calendar pads are generally constituted by a cardboard, plastic or metal sheet onto which the paper sheets are riveted, clipped, sewn or otherwise attached. According to another conventional method of manufacture the sheets are provided with marginal perforations into which assembling rings or an assembling spring may be introduced.

All these manufacturing methods make use of a heterogeneous element constituted by the cardboard support sheet or similar support, by the rivets, the assembling spring or similar assembling element. The necessity of using such heterogeneous elements constitutes a considerable drawback as far as mass production is concerned. Furthermore the clips, eyes, rivets or similar fastening elements present a relief and give the pad an unpleasant appearance which is usually corrected by means of some covering elment such as a glued strip of plastic or decorative sheet material; the provision of this covering element still further complicates the manufacturing process and brings about an increase of manufacturing cost.

Another drawback which is particularly serious in the industry of calendars resides in fact that it is not possible to print an advertising or other pattern onto a conventional calendar or pad after the same has been assembled. Indeed th'e presence of clipping or similar fastening elements prohibits a printing operation on modern automatic printing machines which are designed for continuous printing.

ice" The present invention overcomes these drawbacks and allows homogeneous and perfectly smooth pads to be manufactured at low cost and in accordance with modern mass production techniques, such pads being adapted to receive any desired printed pattern after assembling the pad. Furthermore the pad or calendar manufactured in accordance with the present invention has a particularly attractive aspect, and no complementary element is needed for suspending or fastening the pad.

The present invention has for an object a method of manufacturing a tear-01f calendar, a writing pad, or the like, having a rigid stub and stacked detachable sheets, said method being characterized by the steps of:

Providing sheets having dimensions at least equal to those of the pad to be produced, a marginal portion of said sheets constituting a stub, while the remaining portion of said sheets constitutes detachable sheet portions;

Stacking said sheets while interposing bet-ween any two adjacent sheets at least one film of glue which is activatable by application of heat and which is solid after cooling;

Heating at least the stub constituting portions of said sheets to a temperature at least equal to the glue activating temperature;

Pressing the stack of said sheets by exerting a pressure at least on said stub constituting portions of said sheets while the latter are being heated to the abovementioned temperature;

Cooling the stack to normal ambient temperature; and

Cutting if necessary the thus obtained pad to the desired dimensions.

In accordance with the instant method the pressure applying step may be combined with other operations such as printing a pattern at least onto the front face of the stub, applying a plastic protecting or decorating layer onto the front face of the stub, the forming in the pad of a line of perforations delimiting the stub with respect to the detachable sheet portions and/ or the forming of at least one aperture for suspending the pad by means of a fixing element introduced into the said aperture.

The above method allows for easy manufacture of pads having a stub portion the width of which is comprised between about 0.5 to 15 cm.

Another object of the present invention is the novel industrial product constituted by a pad and more par, ticularly by a calendar with detachable sheets manufactured in accordance with the above defined method.

A pad made in accordance with the present invention has a rigid homogeneous and smooth zone having the same thickness as the detachable sheet portions. Consequently such pad is particularly convenient for all sorts of conventional printing operations. It is also possible to form patterns in relief in the stub portion of the pad during the step of heat and pressure application on a gilding press.

The present invention is particularly advantageous in the field of calendar manufacture. The industry of calendars is a comparatively seasonal industry, and most of the calendars put in the market are provided with publicity patterns. The present invention enables the manufacturer to manufacture entirely assembled calendars in advance and to print on the latter at the last moment, when having received a positive order for a batch of calendars, the advertising pattern which is desired by the user on the stub of such calendars. Such procedure was not possible up to now, using calendars which were manufactured by conventional methods.

Still another object of the invention is to provide a method of manufacturing a tear-off calendar, writing pad, or the like, having a rigid stub and detachable sheets, this method being similar to the one described hereinabove,

except that gluing is not carried out with a glue but by printing on a face of the stub portion of the sheets with a thermoadhesive printing ink.

Such process is particularly advantageous when the detachable sheets h'ave graphic writings such as in the case of tear-off calendars. The thermogluing ink used to print the stub may be constituted by at least one of the printing inks of the sheet portion. In order to reduce the costs of manufacture, the sheets and the stubs may be printed simultaneously and in a continuous operation as, for instance, by means of a conventional offset printing method.

In a preferred embodiment, the various leaves of the assembly to be produced are replaced by one large single sheet the surface area of which is at least equal to the sum of areas of the various leaves. This large single sheet is printed with thermogluing ink at least in the stub portion of the leaves. Thus a black tint block formed by superimposition of the four conventional printing colours may be printed, the colours being possibly applied as a tint block or through a 25, 50 or 75% screen.

When the detachable leave portions are to be printed with carried graphic signs or writings, the portions of the single large sheet corresponding the various leaves are printed simultaneously, the thermogluing ink to print the stub portions being constituted by at least one of the printing inks of the detachable leave portion. The printing is advantageously effected by offset.

The thus printed single large sheet is then cut to the size of the leaves. The cut leaves are stacked and the stub portions thereof are heated to a temperature at least equal to the temperature at which the ink begins to glue. The stacked leaves are then pressed at their stub portions while the same are in heated condition, generally under a pressure of about 2-4 kg./cm. during about one to two seconds. The stacked leaves are then allowed to cool to normal room temperature. A pad of leaves having a rigid stub is thus obtained.

During or after compression of the stub portion, a line of small holes may be formed in the pad to facilitate the separation of the detachable leave portions from the stub portions thereof. One or two holes may also be cut in the upper part of the pad to hang the pad by means of a hanging device passing through said hole(s).

Examples of thermogluing inks useful in the process are conventional inks containing rosin, linseed oil, coumarone resins, rubber resins, synthetic varnish, hydrocarbons. Such inks may be coloured directly with usual pigments.

The thermal conductibility of the inks may be advantageously increased by adding thermoconductive substances such as powdered metals, carbon black.

Such thermoconductive inks permit a best distribution of heat during thermogluing, thus requiring relatively lower temperatures or shorter thermogluing times, or allowing simultaneous thermogluing of several pads stacked one on the other between two heating plates of a press. Fifteen to twenty pads having each 6 sheets may thus be processed together in a two-minute operation under only one press. If the number of pads processed together is from 25 to 30, they must be then pressed again during one minute to improve gluing.

The invention will be better understood in the light of the following description and when studying the appended drawings which show several embodiments of the invention, which are given as examples only and not to be construed as limiting the scope of the invention.

FIG. 1 is a diagrammatic and perspective view of the pad made in accordance with the present invention.

FIG. 2 is a diagrammatic view of a stack of sheets as used in the course of the manufacturing of a pad.

FIGS. 3 and 4 are views similar to FIG. 2, showing other embodiments of the instant pad.

FIG. 5 is a view of a single large sheet for providing detachable sheets to be glued by inking.

FIGS. 6 and 7 represent two embodiments of the large sheet of FIG. 5.

The pad shown in FIG. 1 comprises a rigid stub 1 connected to detachable sheets or sheet portions 2 delimited with respect to the stub portion 1 by a line 7 of perforations or a similar line of weakness. The stub 1 is obtained by assembling sheets 2 provided with glue and submitted to pressure and heat. For better illustration the first sheet is shown partially detached at 8 along the line of perforations 7, and turned over at 5 so as to show the layer of glue 4. The stub 1 is provided with an aperture 9 for suspending the pad, and with a printed pattern 10.

The diagrammatic view of FIG. 2 shows the mode of stacking sheets 2 provided with glue as at 4, prior to pressure application with a view to assembling the pad.

When carrying out this embodiment of the instant method one of the sheets needs not be provided with glue, as indicated at 11.

It is also possible to provide glue films on the two faces of every other sheet, as indicated in FIG. 3.

In accordance with another embodiment the sheets constituting the pad are not provided with glue films but separated from each other by interposed sheets 12 having glue films each on their two faces. Only the zone indicated by reference numeral 13 is then glued under application of heat with a view to forming the stub of the pad.

The manufacture of the instant pad may be carried out without any difiiculty, and conventional machines and equipment used. The glue used for manufacturing the pad of the present invention may advantageously be the one sold under the trademark Hot Melt by the French film Bostik. This thermoplastic glue is applied on the sheets in accordance with the procedure prescribed by the manufacture; it dries immediately and is then of a nontacky consistency.

It is also possible to use a glue applied at low temperature, such as the glue sold under the trademark CX 400 by the French company Teroson et Protection Chimique.

Such glue constitutes after drying a nonadhesive layer at normal ambient temperature.

The above described layers or films of glue become highly tacky or adhesive when heated to a temperature of about -l10 C. Upon consecutive cooling they become hard.

The laminate assembly constituted by the gluing of the sheets under heat forms a hard laminate structure having satisfactory mechanical resistance properties. The outer surface may easily be printed upon, so as to provide a graphical pattern on the uppermost sheet.

Applying the glue only on the portion which is to constitute the stub is advantageous from the economical point of view; however this procedure has the drawback of calling for accurate work so as to avoid the formation of specks on the sheets.

Consequently it may be more advantageous to provide the whole surface of the sheets with glue and to assemble said sheets under heat application only in the portion which is to constitute the stub. Also it is possible to use interposed sheets as shown in FIG. 4. Such interposed sheets may be manufactured in advance and stocked until the time of manufacturing the pad. The interposed sheets may be manufactured on continuous gluing machines of the conventional type, which are entirely automatic; this procedure allows the interposed sheet to be produced at an extremely reduced cost. In many cases it may be advantageous to use interposed sheets having dimensions equivalent to those of the sheets of the pad; because their juxtaposition and the assembly may then be cheaper than the use of double faced adhesive strips having the same width as the stub.

One may also use in the manufacture of the instant pad sheets or interposed sheets which are prepared from pulp containing a heat activatable glue, the latter being present in the pulp in the form of a natural dispersion,

which is the dispersion of a substance under natural conditions, or in the form of micro capsules in accordance with conventional techniques. The gluing operation under application of heat may be carried out in accordance with well-known processes using for instance heated rollers, automatic presses wherein a plurality of heated plates apply pressure to one pad at a time, or heating precise applying such pressure to a plurality of pads, for instance twelve pads at a time, such pressure being applied during 1 to 2 minutes and the pressure being about 2-4 kg./cm. The assembling operation which may be combined with the printing of advertising patterns or relief patterns may also be effected on conventional gliding machines which may be used in connection with perforating machines. When such gilding machines are used the stub of the pad may also be provided with a plastic layer by superimposing thereto a sheet of thermoplastic material. The stub of the pad according to the invention may have a width of several centimeters so as to allow an advertising or other pattern to be printed theren; it may also have a width not exceeding 0.5 to 1 cm. as in the case of conventional calendars of the smaller type.

The area of a single large sheet 14, as represented on FIGS. 5, 6 and 7, is at least equal to the sum or areas of small sheets 15, 16 forming the pad.

A strip 17 or strips 17 and 17 of the sheet 14 corresponding to the stub of small sheets 16 are printed by offset. The stub of the small sheet 15 which will form the front side (recto) of the pad remains unprinted. The ink used is a black thermogluing ink which is a mixture of 66% varnish sold under trademark Fast Glow and 33% heat-conductive black pigment, sold under trademark Superconcentr by Damprene.

The portion of sheets 15, 16 forming detachable sheets may be printed simultaneously with the stub.

In FIG. 5, are represented months of the year which may be decorated with drawings, graphic printings, etc. This printing may be made in colours by means of the three primary colours and of the black colour. For blue, yellow and red colourations a mixture of equal parts of pigments Europa 100 of France Couleurs and varnish Fast Flow of Damprene is used. For black colouration, the ink used is the above-mentioned ink to print the stub. Large sheet 14 is cut to the size of the small sheets, along the dotted lines on the drawings. The cut sheets are stacked, the sheet 15 being the upper one. The stacked sheets are heated to a temperature of about 80- 100 C. and pressed under a pressure of about 2-4 kg./ cm, during 1-2 seconds.

A pad having a rigid stub and detachable sheets is thus obtained in a simple and economic way. Graphic signs, for instance advertisements, may then be printed on the stub of this pad.

What is claimed:

1. The method of producing a tear-01f calendar, writing pad, or similar assembly of superposed sheets, each of said sheets having a top edge, a marginal portion comprising said top edge, and a body portion detachable from said marginal portion along a line of perforation parallel to said top edge, said method comprising printing a film of thermo-adhesive printing ink onto substantially the entire surface area of one face of said marginal portion of each sheet of the assembly to be produced and simul taneously printing with the same thermo-adhesive printing ink a design, indicia, or lettering onto the corresponding face of said detachable body portion of each sheet, assembling the printed sheets with the marginal portions thereof in a superposed relation, heating the superposed marginal portions to a temperature at which the ink printed thereon becomes adhesive, pressing the superposed marginal portions together while the same are in heated condition, and cooling the assembled sheets down to ambient temperature, whereby to produce an assembly having a comparatively rigid stub portion constituted by the thus united marginal portions of the superposed sheets.

2. The method according to claim 1, wherein said thermo-adhesive printing ink includes a thermo-conductive substance.

3. A method of producing a tear-off calendar, writing pad, or similar assembly of superposed printed leaves attached together at a marginal strip portion thereof, and having each a body portion detachable from said marginal strip portion comprising: providing single sheet having a surface area at least equal to the sum of the surface areas of the individual leaves to be assembled, printing a film of a thermo-adhesive ink onto said single sheet within surface areas thereof corresponding each to substantially the entire surface area of the marginal strip portion and simultaneously printing with the same thermo-adhesive ink a design, indicia, or lettering onto said single sheet within surface areas thereof corresponding each to the detachable portion of one of said leaves to be assembled, respectively, separating the printed surface areas of said sheet from each other so as to constitute the printed leaves to be assembled, assembling said printed leaves with said marginal strip portion thereof in superposed relation, and activating the thermo-adhesive ink printed on said marginal strip portions so as to attach said strip portions together and thereby constitute a comparatively rigid stub.

References Cited UNITED STATES PATENTS 2,557,723 6/1951 Brenn 156-291 3,189,702 6/ 1965 Wall et a1. 156272 3,162,116 12/1964 Weber 156-309 DOUGLAS J. DRUMMOND, Primary Examiner US. Cl. X.R. 

